a) Field of the Invention
The present invention relates to a head protection device in a data recording circuit in which write-current is supplied to a magnetic head, which acts on a data storage section of a data storage medium, and a card reader having the head protection device.
b) Description of the Related Art
Generally, magnetic data on magnetic strips or the like] that represent a magnetic recording section formed on a data storage media (e.g. magnetic card), are recorded and reproduced utilizing a magnetic head. Lately, two types of coercivity levels, a high end and a low end, have been standardized for use in a magnetic recording section. For example, in the area of magnetic cards, in addition to conventional low-coercivity cards (300 Oe, 650 Oe) under JIS (Japanese Industrial Standards) or ISO (International Standardization Organization), high coercivity cards (2500-4200 Oe) have been newly standardized. Herein, the use of a high coercivity magnetic recording section is advantageous from the standpoint of protection of magnetic data recorded in a magnetic recording section. However, it has the drawback that a device equipped with a magnetic head that reads or writes a high coercivity magnetic recording section (hereinafter referred to as “a high coercivity magnetic head”) must be readily available. In addition, the magnetic head that reads or writes low coercivity (hereinafter referred to as “a low coercivity magnetic head”) requires a circuit different from that used for a high coercivity magnetic head, therefore, separate devices, one for low coercivity and the other for high coercivity, must be prepared for alternate use.
To solve the problem presented in prior art, the inventor of the present invention developed a data recording circuit, where write-current is supplied to a magnetic head that alternately generates write-current that corresponds to each of the low and the high coercivity magnetic heads. Note that the data recording circuit is not known to the public at the time of filing this patent application.
More specifically the data recording circuit, that can accommodate both a low coercivity magnetic head and a high coercivity magnetic head operates in the following manner. FIG. 3, for example, illustrates that alternate write-current supply portion 2 is provided on the output side of CPU 1, where two types of write-currents are alternately output. Either a low write-current (Lo-Co Current) or a high write-current (Hi-Co current) from low voltage source 2a and high voltage source 2b respectively, flows into common output portion 3. Common output portion 3 is provided by CPU 11 with recording data signal S1 and recording gate signal S2 such that a low coercivity magnetic head 4 or high coercivity magnetic head 5 obtain each S1 and S2 by means of the above-mentioned Lo-Co current or Hi-Co current.
Herein, a low coercivity magnetic head 4 and a high coercivity magnetic head 5 can be alternately attached to or removed from common output portion 3. Both the low coercivity magnetic head and the high coercivity magnetic head can be alternately used in a single device, thereby reducing capital cost and providing an easy-to-use feature.
Nonetheless, the concept of one device having both a low coercivity magnetic head and a high coercivity magnetic head in an interchangeable manner has the drawback in that erroneous recognition occurs of whether it is a high coercivity magnetic head or a low coercivity magnetic head that is connected thereto. Particularly, when a low coercivity magnetic head is connected to the device, the circuit can be erroneously set up for Hi-Co current for a high coercivity magnetic head. Even if the setting is correct, there is concern about errors on the circuit side or the CPU that they might allow an excessive amount of current to flow into the low coercivity magnetic head, damaging the head or circuit.